1. Technical Field
This invention relates generally to cleaning devices. More particularly, this invention relates to a device, system and method for cleaning tubes, especially heat exchanger tubes. Specifically, this invention is directed to a hose reel assembly having an inner drum rotatable in one of two directions to wind or unwind a hose disposed in a gap between the inner and outer drums onto or off of the inner drum; and an outer drum rotatable to cause rotation of a nozzle on a hose attached to the assembly about that hose's longitudinal axis and at speeds of about 100 rpm to about 1600 rpm in order to deliver a pressurized jet of water to cut through deposits in the heat exchanger tubes.
2. Background Information
Heat exchangers are devices that transfer heat or cold from one fluid to another. There are several different types of heat exchanger which are used in different applications but one of the more commonly used forms is known as a shell and tube heat exchanger. In this device, there is provided an external shell having an interior chamber within which is disposed a plurality of tubes. The tubes are positioned substantially parallel to each other in a group known in the industry as a tube bundle. Each tube in the tube bundle is surrounded by open space which separates the tube from adjacent tubes. A first fluid is caused to flow through the bores of the tubes and a second fluid is caused to flow through the chamber of the shell in which the tube bundle is situated. If the first fluid is hotter than the second fluid then as the second fluid flows through the chamber and through the spaces surrounding the tubes, heat from the first fluid is transferred to the second fluid. Shell and tube type heat exchangers are designed to maximize the heat transfer between the first and second fluid. Some of the factors that have to be considered in the design of the system are the length of the tubes, the external diameter of the tubes relative to the space surrounding the tubes and the diameter of the bore through each tube. It has been found that longer, thinner tubes offer substantial heat transfer.
One of the issues that these systems experience is that the heated fluid flowing through the tubes tends to deposit impurities onto the interior surfaces of the tube wall that defines the bore. The impurities build up over time and narrow the bore, thus restricting the flow of fluid therethrough. The slowing of the fluid flow tends to accelerate the rate of deposition on the tube walls, restricting the flow even further. This leads to a loss of efficiency in the system. This fouling is especially problematic when long, thin tubes are utilized in the tube bundle.
It is therefore necessary to periodically clean the tubes to remove the built-up substances from the interior surface of the tube's walls. There are several known methods for undertaking this cleaning. In some instances, devices such as small foam balls or other mechanical “blasting-type” materials are placed into the stream of the fluid that will flow through the tubes. These materials scour the interior surfaces, knocking small pieces of built-up substances from the same. In other cleaning methodologies, chemical cleaners are pumped through the tubes to dissolve the build-up. In other instances, drill-type rods are inserted into the tube bores to remove the deposits or high-pressure water jets are used to blast material from the tube's interior surface. The delivery of this high pressure, high velocity water to cut through the deposits presents somewhat of a safety issue for the operators of the machinery accomplishing the cleaning. The narrowness or even blockage of the bores of some of the tubes can cause the water jet to be deflected back toward the operator, potentially injuring him or her. There is also a tendency for the water jet to simply cut a channel through the built-up material instead of scouring the interior surfaces of the tube clean.
There is therefore a need in the art for an improved device for cleaning heat exchanger tubes using a high pressure, high velocity water jet that quickly and efficiently scours substantially the entire interior surface of a heat exchanger tube while doing so in a safe manner for the operator of the cleaning device.